Heat Sends U.S. Nuclear Power Production to 9-Year Low

The Vermont Yankee Nuclear Power Plant on the Connecticut River, a 620-megawatt plant operated by Entergy Corp., reduced power to 83 percent of capacity on July 17 because of low river flow and heat. Photographer: CJ Gunther/epa/Corbis

July 26 (Bloomberg) -- Nuclear-power production in the U.S.
is at the lowest seasonal levels in nine years as drought and
heat force reactors from Ohio to Vermont to slow output.

Generation for the 104 plants in the U.S. fell 0.4 percent
from yesterday to 94,171 megawatts, or 93 percent of capacity,
the lowest level for this time of year since 2003, according to
reports from the U.S. Nuclear Regulatory Commission and data
compiled by Bloomberg. The total is down 2.6 percent from the
five-year average for today of 96,725 megawatts.

“We’ve had a fast decay of summer output this month and
that corresponds to the high heat and droughts,” Pax Saunders,
an analyst at Gelber & Associates in Houston, said. “Plants are
not able to operate at the levels they can.”

FirstEnergy Corp.’s Perry 1 reactor in Ohio lowered
production to 95 percent of capacity today because of above-average temperatures, while Entergy Corp.’s Vermont Yankee has
limited output four times this month. Nuclear plants require
sufficient water to cool during operation, and rivers or lakes
may get overheated or fall in times of high temperatures and
drought, according to the NRC.

Dry conditions have worsened in the past week, with at
least 63.9 percent of the contiguous 48 U.S. states now affected
by moderate to severe drought, the U.S. Drought Monitor said
today. That compares with 63.5 in the previous week.

High Temperatures

Temperatures will rise about 3 degrees above normal in the
U.S. Northeast from Aug. 4 to Aug. 8 and computer modeling shows
another heat wave may arrive the week of Aug. 6, according to
Commodity Weather Group President Matt Rogers.

“Heat is the main issue, because if the river is getting
warmer the water going into the plant is warmer and makes it
harder to cool,” David McIntyre, an NRC spokesman, said.

Production at FirstEnergy’s 1,261-megawatt Perry 1 reactor
dropped by 63 megawatts early today in preparation for high
temperatures and humidity, according to Todd Schneider, a
company spokesman in Akron, Ohio.

The region is under a weather advisory from noon to 7 p.m.
today, with heat index values as high as 102 degrees Fahrenheit
(39 degrees Celsius), according to a report from AccuWeather
Inc. Perry 1, 35 miles northeast of Cleveland, has slowed
production four times since July 1.

Fluctuating Output

“Output has fluctuated throughout July because of the
weather conditions including outside temperature and humidity,”
Schneider said by phone today. “The higher temperatures make it
more difficult to run at 100 percent.”

Vermont Yankee, the 620-megawatt plant operated by Entergy
Corp., reduced power to 83 percent of capacity on July 17
because of low river flow and heat, according to Rob Williams, a
company spokesman based in Brattleboro, Vermont.

The reactor has lowered generation at least once every week
since July 1, according to commission data.

“We’ve been having to do it with the warmer weather
conditions,” Williams said. “The weather dictates how much
electricity we can produce and it’s the nature of doing business
on a river with variable flow and variable temperatures.”

Exelon’s Byron 1 and Byron 2 plants in Illinois have been
operating below full capacity since June 28, according to
filings with the NRC and data compiled by Bloomberg. The plants
are preparing for a yearlong maintenance project that will
upgrade equipment inside the cooling towers.

Byron Output

Generation at the 1,164-megawatt Byron 1 reactor slowed to
80 percent of capacity today, while Byron 2 operated at 84
percent. Production has fluctuated because adjustments to
cooling tower operations vary with weather conditions, Paul
Dempsey, communications manager at the plant, said by phone from
Byron, Illinois.

As long as the heat persists, Saunders of Gelber &
Associates expects nuclear supply to stay low while demand
continues to climb.

Hotter-than-normal weather in the large cities along the
East Coast usually raises demand for electricity as people turn
to air conditioners to cool off. Generation in the region was
24,043 megawatts today, 3.8 percent lower than a year ago.

Production in the Southeast was 4.9 percent lower than a
year earlier, compared with 6.6 percent for the Midwest and 4.1
percent for the West, according to commission data.

“We expect the trend of things getting tighter and tighter
to persist,” Saunders said in a phone interview. “The impact
of the last few weeks have been the largest of the summer.”